I have a 05 Supercharged SS that recommends premium in the manual. I'm looking for technical info that supports a certain octane level.
My other car is a Supercharged Corvette so I understand octane requirements but this car is driven a lot of hwy miles by my wife, neverhits boost, and the premium is expensive if 89 octane will suffice...............opinions please????

Thanks,
Randy

 

I have an 04 supercharged and alternate the fuel. If I am just commuting back and forth to work or just driving on the highway I use regular or mid-grade. If I am feeling a lead foot coming on I will use premium. As long as your foot is not in the peddle all of the time you will be allright using less then premium.

If you run regular and have your foot in it all of the time you could cause damage to the engine.

Others may differ with this, but it seems to work well for my situation.

 

I believe 91 octane is what is recommended by GM.

 

If you run 89, scan for knock. Period. on 89, your engine WILL knock under boost, and more than likely, enough to start chipping pistons.

Lets see.. 89 octane.. 3.09.
93 octane 3.29.

new engine? 1200.00

is it worth saving 20 cents a gallon to risk blowing your engine, not to mention voiding factory warranty, and taking a chance at losing a beautiful car? nope.

Just my opinion, but if you wanna run just 89, may as well just pull the supercharger, and toss 87 in it.

 

At 20 cents a gallon difference, if it holds 17 ga. like mine, then you save $3.40 per tank if bone dry.
My mom used to dry me crazy. We had a 3 cylinder Geo Metro (= EXCELLENT mpg), We always used it to go to Kansas and she would drive around trying to find the cheapest gas. The difference was usually only about 3 cents a gallon difference, the car held a whopping 9 gallons, so she was saving, at most, a grande total of 27 cents. I finally told her, it's our car, I'll pay the difference, LOL. (we used our, mine & hubby's, car and she paid for the gas)

 

well about hte high grade thing... every station i see around here, except for some in norfolk, the difference has always been 20 cents a gallon. from tiem to time its 24 or 26... but most of the time its 20. so... no matter what the price of gas, its really just another $3.40 on top of that to fill up....

I go along with Keegan... $3.40 at every fill up or a new engine at $1200? As a matter of fact, $1200 sounds kind of low.. that just the engine. what about the downtime?

I've run 87 and 93 in my naturaly aspirated engine. i get 2 miles better per gallon. until it costs about $8-10 more dollars to fill up my car with 93, the higher grade is paying for itself.

btw, don't trust that comptuer. some people here claim theres is spot on... thats all well and good, and i hope they are glad. mine is about 1.5-2 miles off.

 

I took that into consideration when I bought this car. I figured it would cost me about $1,000 more over the 3 years I intend to drive this commuting. I bought this car CHEAP, so I just figure that is part of the monthly expense of driving, like tires, LOF, and other maintenance, and of course the payment. Hard to figure in the costs of the modding, tho.
I run ONLY 93 octane Top Tier gas, either Amoco Ultimate, Shell V-power, or in a bind, Citgo premium. I NEVER run independent generic gas.

 

You're right. 1200 is for a USED engine. A brand new one, not including heads (which also could be damaged from knock) runs from GM:

Engine, impala, monte carlo, federal, w/supercharger - 3.8l - 3.8L 2004 N/A $2,719.60

Granted, perhaps a little overkill to get a new engine. But if it chips, you're looking at pulling the engine, having to bore it over .10, along with buying new pistons (900-1000) along with having to completely re-assemble the engine, etc. Is it worth the above said 3 dollars per fill up? If you are THAT short on cash, I WILL HELP TO PAY YOU. And if you are still THAT hard up to save your engine from failure, sell it, and buy a standard non s/c 3800.

 

I always put Sunoco 94 octane in my 04 Supercharged SS. Firstly because of what the others have mentioned about how expensive a damaged engine is to fix or replace. But also I like the extra "oomph" I get from the higher octane.

 

Hmm.. That would give me an excuse to upgrade to the Diamond Pistons to run more boost....